The present invention relates to a damping strut for a bicycle.
A damping strut for a bicycle, such as a trekking bicycle or a mountain bicycle or other land vehicles is conventionally known in combination with a suspension strut as a wheel suspension. Conventionally, the damping strut is configured in a hydraulic design, wherein the damping strut is, for example, a single-tube damper filled with a damping fluid. Mounted longitudinally displaceable in the single-tube damper is a damper piston for displacing the damping fluid, the damping piston having a plurality of damping apertures. When the damping strut travels in and out, the damping piston is displaced in the single-tube damper so that the damping fluid is displaced by the damping piston such that the damping fluid flows through the damping apertures. The flow of damping fluid in the single-tube damper, particularly through the damping apertures is subject to losses, with the result that a damping force is produced which counteracts the displacement of the damping strut.
When the bicycle is used in a variety of driving situations, demands are placed on the damping strut, particularly in respect of the level of the damping force, with which riding the bicycle with safety and a high degree of comfort is possible. It is therefore desirable, if, for example, a wheel passes through a pothole, that both when the wheel passes into the pothole and when the wheel passes out of the pothole, the damping force is as small as possible. It is also desirable that, for example, when passing over an obstacle, as the wheel rides up onto the obstacle, and the damping strut is elastically contracted, the damping force increases progressively, particularly advantageously in the last third of the maximum stroke of the damping strut, thus preventing the danger that the damping strut travels beyond the maximum stroke thereof and consequently “bottoms” and, as the wheel rides off the obstacle, as the damping strut expands elastically, the damping force is as high as possible so that the horizontal position of the bicycle remains unchanged on passing over the obstacle. It is also desirable that, if a person is seated on the bicycle and the wheel suspension units yield under the weight of said person, the demands placed on the damping force are also sufficiently achievable. In the case, particularly, of damping struts for bicycles or other lightweight vehicles, it is greatly advantageous if, due to the very large rider mass relative to the vehicle mass, the damping forces of the damping strut are dependent on a gas pressure of a gas pressure spring acting in parallel with the damping strut and pre-settable by the rider, in particular to adjust to the mass of the rider, and the level of the damping forces therefore adapt automatically in the correct proportion to the spring stiffness of the gas pressure spring strut, whilst retaining the characteristic stroke-dependent response thereof.